Urethral Calculus

Urethral calculus is a stone lodged within the urethra.

• Secondary (migratory) stones form in the kidneys or bladder and lodge during passage: 90 percent of cases, in men, usually in the posterior urethra (prostatic or bulbar) or fossa navicularis.
• Primary (autochthonous) stones form in the urethra above a stricture, diverticulum, fistula, foreign body or abnormal urinary stasis, and are common in endemic areas of Africa and the Middle East with urinary schistosomiasis and malnutrition.
• Female urethral stones are rare and linked to urethral diverticulum or foreign body.

Sudden pain in the urethra or penis, acute urinary retention (commonest), dysuria, poor or interrupted stream, haematuria, terminal haematuria, dribbling.

• Hard palpable mass along the urethra or at the meatus; pain at the glans, perineal pain; haematuria on voiding.
• Differential diagnosis: urethral stricture, urethral foreign body, urethral tumour or polyp, posterior urethral valves, urethral diverticulum, prostatitis, bladder stone, blood clot retention, benign prostatic hyperplasia.
• Complications: acute retention, urethral injury and stricture, urinary tract infection, periurethral abscess, urethral fistula, Fournier gangrene, hydronephrosis and renal failure, recurrence.

Examination: palpation along the urethra and per rectum.

• Urinalysis and culture; creatinine.
• Plain radiograph of kidneys, ureters and bladder to the perineum shows radio-opaque stones; ultrasound (shadowing stone); retrograde urethrogram shows a filling defect and stricture or diverticulum; CT in doubt; urethroscopy confirms.
• Look for the source (bladder and upper tract stones) and associated stricture or diverticulum.

Supportive: analgesia (diclofenac 75 mg IM, paracetamol 1 g IV), local anaesthesia, relief of retention by suprapubic catheter if urethral access fails; avoid forceful instrumentation.

Pharmacological

• Lidocaine 2 percent jelly 10 to 20 mL instilled into the urethra with a penile clamp to lubricate and anaesthetise.
• Antibiotics for infection or after instrumentation: ciprofloxacin 500 mg twice daily or cefixime 400 mg daily for 5 to 7 days (gentamicin 5 mg/kg IV once if septic).
• Treat metabolic risk factors for stone recurrence.

Procedures

• Fossa navicularis or distal stone: milking out the stone after lubrication, extraction with forceps or an alligator forceps, meatotomy or meatal dilation if the stone is larger than the meatus.
• Anterior and mid urethral stone: retrograde cystoscopic flushing and extraction with a basket or forceps, or laser (holmium) or pneumatic lithotripsy in situ; urethrotomy for impacted stone with stricture.
• Posterior urethral stone: push back into the bladder with a catheter or flexible cystoscope (urethral catheter or sound), then remove it by cystolitholapaxy or suprapubic cystolithotomy.
• Urethrotomy, urethrostomy or urethroplasty for stone-bearing stricture or diverticulum; excision of diverticulum.
• Avoid external urethrotomy for simple stones.

Special groups: children (primary stones, schistosomiasis, malnutrition; cystoscopic retrieval), women (cystoscopy; diverticulectomy), patients with neurogenic bladder (catheter care).

Red flags: perineal swelling or infection (urinary extravasation), urosepsis, anuria, rising creatinine.

Follow-up: urethrography or flexible urethroscopy at 3 months for stricture; stone analysis and metabolic evaluation; hydration advice; praziquantel 40 mg/kg single dose in schistosomiasis.